WO2000015009A1

WO2000015009A1 - Light source and display device

Info

Publication number: WO2000015009A1
Application number: PCT/JP1999/004752
Authority: WO
Inventors: Osamu Yokoyama; Satoru Miyashita; Tatsuya Shimoda; Yasunori Taga; Shizuo Tokito; Koji Noda
Original assignee: Seiko Epson Corporation
Priority date: 1998-09-02
Filing date: 1999-09-01
Publication date: 2000-03-16
Also published as: EP1039784A1; EP1039784B1; EP1039784A4; US7205964B1; DE69930646D1; KR100533451B1; JP2008276258A; DE69930646T2; CN100340136C; KR20010031677A; TW548483B; ATE322143T1; CN1287768A

Abstract

A red EL (10R), a green EL (10G) and a blue EL (10B) for emitting red, green and blue light are arranged on the back of liquid crystal display elements (11R, 11G and 11B) that display primary colors, respectively. The ELs are organic EL elements that include organic luminescent film. Each of the EL elements comprises an organic luminescent layer (14) interposed between ITO electrodes (13) and metal electrodes (15), which are in the form of mutually perpendicular stripes, and light is emitted from the intersections (luminescent points) of the stripes of the ITO and metal electrodes. The luminescent points are arranged two-dimensionally on a glass substrate (12) to illuminate the whole display area of the liquid crystal display elements.

Description

Description Light source and display device

The present invention relates to a light source for illuminating a display element and a driving method thereof, and a display device for illuminating a display element with the light source to perform display.冃

Japanese Patent Application Laid-Open No. 51-119243 discloses a technique for reducing the size of a projection-type liquid crystal display device that displays an image of a liquid crystal display element by enlarging and projecting it. In this publication, a flat panel light source such as an electroluminescent element (hereinafter referred to as EL element) illuminates the liquid crystal display element, magnifies the image displayed on the liquid crystal display element with a lens, and projects it on a screen. A configuration of a display device is disclosed.

In recent years, the development of organic EL devices using an organic thin film as a light-emitting layer has progressed, and the emission luminance has been significantly increased. This organic EL element can be an effective light source for constructing a small and bright projection type liquid crystal display device.

However, when the organic EL element emits light continuously with high luminance, the luminance is significantly reduced. One reason for this is that heat is generated by the current supplied to drive the organic EL element, and that heat is accumulated, causing the temperature of the element to rise, and changing the structure and characteristics of the organic thin film. Can be

On the other hand, as a conventional technique for suppressing a decrease in luminance of the organic EL element, Japanese Patent Application Laid-Open No. 7-230880 discloses a technique for driving the organic EL element by pulse driving.

Also, in a display device that illuminates a liquid crystal display element with three organic EL elements that emit red, green, and blue light corresponding to the three primary colors, and enlarges and displays an image displayed on the liquid crystal display element. In addition, it is necessary to make each organic EL element emit light at a high luminance of about 100,000 cd / m2, and to correct the color balance due to the change in luminance of each color, the luminance of each color of the organic EL element is corrected. Need to be controlled independently. Disclosure of the invention

The present invention has been made in view of the above problems, and a first problem of the present invention is to suppress the accumulation of heat in a light source, suppress a decrease in luminance, and improve the brightness of a display image using the light source. It is an object of the present invention to provide a display device in which the reduction in ruin is small.

Further, a second object of the present invention is to provide a display device of a particularly enlarged display type in which a decrease in luminance of a display image is small and a color balance can be corrected.

The first problem is solved by the following light sources or display devices (1) to (7).

(1) A light source comprising a plurality of organic electroluminescent elements arranged one-dimensionally or two-dimensionally on the same substrate, wherein the plurality of organic electroluminescent elements are simultaneously turned on.

According to the light source of the above (1), it is possible to suppress the accumulation of heat generated at the time of light emission in the light source that illuminates a spatially wide area, and to suppress a decrease in brightness of the light source. .

(2) The light source according to (1), wherein the plurality of organic electroluminescent elements emit light in one of three primary colors.

The light source of the above (2) is a light source that emits a single color.

(3) The light source according to (1) or (2), wherein the organic electroluminescent element includes an optical microresonator.

The light source of the above (3) has an effect that a light having a peak of intensity at a specific wavelength and having a strong directivity in the front direction can be emitted.

(4) The light source according to any one of (1) to (3) above, wherein an anode formed on the substrate in a stripe shape in a first direction, and a second electrode orthogonal to the first direction. A light source characterized in that the organic electroluminescent element is formed at an intersection with a striped cathode formed in a direction.

According to the light source of (4), a light source having a simple structure in which the light emitting elements are arranged discretely in two dimensions can be easily realized.

(5) The light source according to any one of (1) to (3) above, wherein a light emitting unit is provided on the substrate. A light source, wherein the light sources are arranged one-dimensionally.

In the light source of the above (5), the area of the light emitting region is larger, the accumulation of heat during light emission is suppressed, and high luminance can be maintained.

(6) A display device, wherein a display element is illuminated by the light source according to any one of (1) to (5).

According to the above-described display device, a high-performance display device in which the luminance is hardly reduced due to the characteristics of the light source is realized.

(7) The display device according to (6), wherein a distance between the adjacent organic electroluminescent elements in the light source is P, and a distance from the organic electroluminescent element to a display surface of the display element is D. A display device, wherein D is at least 10 times P.

The display device has an effect that spatial uniformity of illumination light for illuminating the display surface of the display element can be improved.

(8) The display device according to any one of (6) and (7), wherein the display element is a liquid crystal display element.

The display device has a simple structure and high luminance.

The second object of the present invention is solved by the following display devices (9) to (16).

(9) In a display device comprising an organic electroluminescent element as a light source, a display element illuminated by the light source, and an optical system for enlarging and displaying an image displayed on the display element, the organic electroluminescent element A display device, comprising: a light-emitting region having a size substantially equal to a display region of the display device; and a noble current supplied to the organic electroluminescent device to cause the organic electroluminescent device to emit light. .

According to the display device of the above (9), it is possible to suppress an increase in the device temperature due to heat accumulation in the organic electroluminescent device, and it is possible to suppress a decrease in emission luminance, that is, a decrease in brightness of a display image. The effect is brought.

(10) A first organic electroluminescent element that emits light in the red region, a second organic electroluminescent device that emits light in the green region, and a third organic electroluminescent device that emits light in the blue region. And the first, second and second illuminated by their respective organic electroluminescent elements A display device, a combining optical system for combining images displayed on the first, second, and third display devices, and an optical system for enlarging and displaying the image combined by the combining optical system. Wherein the first, second, and third organic electroluminescent elements each have a light-emitting area substantially equal in size to the display areas of the first, second, and third display elements. A display device, wherein a pulse current is supplied to each of the first, second, and third organic electroluminescent elements to emit light. The display device of the above (10) is particularly suitable for a display device having a high resolution of a display image, in which an increase in element temperature due to heat accumulation in an organic electroluminescent element as a light source is suppressed, a decrease in emission luminance, That is, an effect is brought about when the decrease in the brightness of the display image is suppressed.

(11) The first organic electroluminescent device emitting light in the red region, the second organic electroluminescent device emitting light in the green region, and the third organic electroluminescent device emitting light in the blue region A synthetic optical system for synthesizing the ¾M light from each of the organic electroluminescent elements, a display element illuminated by the light synthesized by the synthetic optical system, and an image displayed on the display element. A display device including an optical system for displaying, wherein the first, second, and third organic electroluminescent elements include a light-emitting area substantially equal in size to a display area of the display element; A display device, wherein a pulse current is supplied to each of the organic electroluminescent elements to cause the second and third organic electroluminescent elements to emit light.

The display device of the above (11) is a display device for projecting a color image using a single display element, which suppresses a rise in element temperature due to heat accumulation in an organic electroluminescent element as a light source, and emits light. An effect is brought about when the decrease in luminance, that is, the decrease in brightness of the displayed image is suppressed.

(12) The display device according to any one of the above (9) to (11), wherein the display element is a liquid crystal display element.

In the above display device, high-definition display with a simple structure is possible.

(13) The display device according to any one of (9) to (11) above, wherein a peak current, a frequency, and a frequency of the pulse current are adjusted to adjust the luminance of the organic electroluminescent element. A display device, wherein at least one of a pulse width is controlled.

The display device has an effect that the luminance can be kept constant for a certain period of time by compensating for a decrease in the luminance of the light source.

(14) The display device according to the above (10) or (11), wherein the display device is supplied to the first, second, and third organic electroluminescent elements in order to adjust a color of a display image. A display device, wherein at least one of a peak current, a frequency, and a pulse width of the pulse current is independently controlled for each organic electroluminescent element.

The display device has an effect that the luminance of the light source of each color can be adjusted independently, and the color balance can be adjusted.

(15) The display device according to any one of (9) to (14), wherein the organic electroluminescent element has an optical microresonance structure.

The above-described display device has an advantage that the color purity of a display image can be increased and the light use efficiency is improved.

(16) The display device according to (10) or (11), wherein a pulse is supplied to each of the first, second, and third organic electroluminescent elements. A display device that is the same.

In the above display device, the balance of display colors is improved.

Further, according to the present invention, the following display devices (17) to (19) are provided.

(17) A plurality of organic electroluminescent elements arranged one-dimensionally or two-dimensionally are formed on the same substrate, and the plurality of organic electroluminescent elements are illuminated by a light source that is simultaneously turned on, and the light source. In a display device including a display element and an optical system for enlarging and displaying an image displayed on the display element, a pulse current is supplied to the organic electroluminescent element to cause the organic electroluminescent element in the light source to emit light. A display device characterized in that:

(18) A plurality of first organic electroluminescent elements which emit light in a plurality of red regions arranged one-dimensionally or two-dimensionally on the same substrate are formed, and the plurality of organic electroluminescent elements are simultaneously turned on. Forming a first light source and a second organic electroluminescent element that emits light in a plurality of green regions arranged one-dimensionally or two-dimensionally on the same substrate; A second light source in which the organic electroluminescent elements are turned on at the same time, and a third organic electroluminescent element which emits light in a plurality of blue regions arranged one-dimensionally or two-dimensionally on the same substrate are formed. A third light source in which the plurality of organic electroluminescent elements are simultaneously turned on, at least one display element illuminated by the light source including the organic electroluminescent elements, and an image formed by the display element. A display device comprising: an optical system for displaying; an organic electroluminescent element in the first light source, an organic electroluminescent element in the second light source, and a third organic electroluminescent element in the third light source. A display device characterized in that organic light-emitting devices are supplied with light current to emit light.

(19) The display device according to (18), wherein a pulse is supplied to each of the first, second, and third organic electroluminescent elements at the same timing.

In the display device according to any one of (17) to (19), an increase in device temperature due to heat accumulation in the organic electroluminescent device can be suppressed, and a decrease in emission luminance, that is, a decrease in brightness of a display image can be suppressed. The effect that can be obtained is more remarkable. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a cross-sectional view showing a light source and a main optical system of a display device according to a first embodiment of the present invention.

FIG. 2 is a plan view showing the structure of the light source according to the first embodiment of the present invention.

FIG. 3 is a plan view showing a modification of the structure of the light source according to the first embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a main optical system according to a second embodiment of the display device of the present invention.

5A to 5D are diagrams showing current waveforms for driving an organic EL element as a light source in the display device according to the second embodiment of the present invention.

FIG. 6 is a view showing a modification of the timing of the current waveform for driving the organic EL element as the light source in the display device according to the second embodiment of the present invention.

FIG. 5 is a sectional view showing a main optical system of a display device according to a third embodiment of the present invention. It is.

FIG. 8 is a sectional view showing a main optical system of a display device according to a fourth embodiment of the present invention.

FIG. 9 is a cross-sectional view illustrating a main optical system of a display device according to a fifth embodiment of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of a light source and a display device of the present invention will be described with reference to the drawings.

First, a first embodiment will be described with reference to FIGS. FIG. 1 is a cross-sectional view of a main optical system constituting a projection type liquid crystal display device as a display device according to the present embodiment, and FIG. 2 is a plan view showing a structure of a light source including an organic EL element. is there. Although FIG. 2 shows only seven light-emitting portions 20 and five vertical light-emitting portions 20 each formed of an organic EL element for easy viewing, the actual number of light-emitting portions 20 is increased.

In the structure shown in FIG. 1, the liquid crystal display element 11 R for displaying a red component image, the liquid crystal display element 11 G for displaying a green component image, and the liquid crystal display element 11 B for displaying a blue component image are: The dichroic prism 16 is arranged to face the corresponding surface of the dichroic prism 16. A red EL light source 10R composed of a two-dimensional array of red organic EL elements that emits light in the red region is provided on the back of the liquid crystal display element 11R that displays the image of the red component. The liquid crystal display element that displays the blue component image is a green EL light source 10 G composed of a two-dimensional array of green organic EL elements that emits light in the green region on the back of 1 G. On the back side of 11B, blue EL light sources 10B each composed of a two-dimensional array of blue organic EL elements that emit light at a wavelength in the blue region are arranged.

The image displayed on each liquid crystal display element is illuminated by the EL light source of the corresponding emission color, synthesized as a single color image by the dichroic prism 16, enlarged by the projection lens 17 and enlarged to the screen 18 Displayed as an image.

As shown in Fig. 2, each light source consists of a thin ITO (Indium Tin Oxide) layer formed on a glass substrate 12, ITO®S13, a hole transport layer, a light emitting layer, and an electron It has a laminated structure of an organic light emitting layer 14 composed of a laminated structure of organic thin films such as a transport layer and a metal 5 composed of an alloy of Mg (magnesium) and Ag (silver). Note that these film structures are sealed using another substrate to prevent 'contact with moisture and dust'.

The electrode 3 and the metal electrode 15 have a striped pattern, and the patterns are orthogonal to each other. In each light source, the intersection of the pattern of IT〇S @ 13 and the metal electrode 15 becomes the light-emitting portion 19, the IT 部 electrode 13 becomes the anode, the metal electrode 15 becomes the cathode, and the voltage applied between them becomes A current is supplied to the organic light emitting layer 14, and the light source emits light.

The pattern of I τ 0 m, the organic light-emitting layer and the metal m @@ is not limited to such a pattern, and any pattern in which the light-emitting portions 19 are independently arranged two-dimensionally is preferably used. Can be.

Between the glass substrate 1 2 and亟1 3, preferably S i O ₂ and T i O ₂ are laminated sequentially is formed with a dielectric multilayer film, the dielectric multilayer film and the metal electrodes By forming an optical micro-resonator with the light emitting section 15, the light emitted from the light emitting section 19 can be emitted at a specific wavelength (for example, 6200 nm for a red organic EL element, green organic EL element). It has sharp peaks at 535 nm and 470 nm for a blue organic EL device, and can be light with high directivity in the front direction. By using such an organic EL element, it is possible to increase the purity of a color displayed on a display device and to realize a bright display device with little loss of light when passing through an optical system. Can be. With the light emission of the light source, heat is generated in the light emitting section 19 and heat generated by the current flowing through the IT0 electrode 13 and the metal electrode 15. When the IT OSM, organic light-emitting layer, and metal m @@ are formed over the entire area of the liquid crystal display element that has the same area as the display area, there is no escape for heat, and heat accumulation on the glass substrate, etc. is remarkable. It becomes. On the other hand, by arranging the light emitting units discretely as in the present embodiment, it is possible to alleviate the heat accumulation and the temperature rise of the organic EL element. This makes it possible to suppress deterioration of the organic EL element as a light source.

Furthermore, although not shown, for example, heat conduction is performed on the metal electrode 15 through an insulating film. It is also effective to form a thick film of aluminum, copper, gold, silver, etc., which has good properties, and use it as a heat dissipation path. In particular, it is preferable to provide a heat transfer line in the gap between the light-emitting portions 19 using the above-described material having good heat conductivity, thereby forming a heat dissipation path.

In order to illuminate a display area having a two-dimensional spread in a liquid crystal display device, it is necessary to spatially uniform the brightness of the light emitted from the light emitting units arranged spatially discretely. preferable. This can be realized by increasing the distance (D) between the light emitting unit 19 and the display surface of the liquid crystal display element 11 with respect to the distance (P) between the adjacent light emitting units 19 in the light source. For example, it is more preferable that D is 10 times or more of P.

Next, specific numerical examples will be described. The size of the display area of each of the liquid crystal display elements 11R, 11G, and 1IB shall be 0.9 inches diagonally (18.3 mm in width and 13.7 mm in height). In each of the EL light sources 10R, 10G, and 10B, the distance between the adjacent light-emitting portions 19 (distance between the centers of the light-emitting portions) (P) is 0.3 mm, the ITO electrode 13 having a stripe pattern and the metal electrode The width of 15 is 0.1 mm. In this case, the size of the light emitting section 19 is 0. ImmxO. 1 mm. In order to uniformly illuminate the periphery of the display area, it is necessary to make the area where the light emitting section 19 exists larger than the display area. For example, the width is 20 mm and the height is 15 mm. This area includes about 66 × 50 light emitting portions 19. The thickness of the glass substrate 12 of each EL light source is 1 mm. The distance (D) between the light-emitting portion 19 and each display surface of the liquid crystal display elements 11R, 11G, and 11B should be at least 10 times the distance (P) between the adjacent light-emitting portions 19. Set, for example, 3.5 mm.

The display device of the present invention can be applied to a head mount display and a head-up display in addition to the projection type liquid crystal display device described in the first embodiment. Further, as the display element, a display element other than the liquid crystal display element can be applied. Although a light source that emits red, green, and blue light is used as the light source, a display device that uses one or two EL light sources of red, green, and blue depending on the displayed color is configured. It is also possible.

The light source of the present invention uses an array of organic EL elements as a light source. In the embodiment, the light source having the configuration in which the organic EL elements are two-dimensionally arranged has been described. However, depending on the application, the light emitting portion (region) shown in FIG. It is also possible to have a structure in which 19 ′ is arranged in a three-dimensional manner. In this case, as compared with the case where the light emitting units are two-dimensionally arranged, the brightness of the entire light source is higher, and the heat dissipation from the organic EL element can be secured. Also in this case, it is more preferable that a heat transfer region is provided in the gap between the light emitting regions by using the above-described material having good thermal conductivity to dissipate heat.

As described above, the light source according to the first embodiment of the present invention includes an array of organic EL elements discretely arranged so as not to impair the spatial uniformity of the illumination light of the display element. By doing so, it is possible to suppress the accumulation of heat generated during light emission, and to suppress the deterioration of the light source. In addition, by using such a light source, a compact display device with little decrease in brightness can be configured.

Next, a display device (projection type liquid crystal display device) according to a second embodiment of the present invention will be described with reference to FIGS. 4 and 5 (A to D). Fig. 4 is a cross-sectional view of the main optical system that constitutes the projection type liquid crystal display device. Figs. 5A, B, C and D show the pulse current supplied to make the organic EL element, which is the light source, emit light. It is a figure showing a waveform. The structure of the optical system shown in FIG. 4 is approximately the same as that of the display device of the first embodiment. The liquid crystal display element 21R for displaying the image of the red component, the liquid crystal display element 21G for displaying the image of the green component, and the liquid crystal display element 21B for displaying the image of the blue component It is arranged facing the corresponding surface. On the back of the liquid crystal display element 21 R displaying the image of the red component, there is a red organic EL element 2 OR emitting light at a wavelength in the red region, and on the back of the liquid crystal display element 21 G displaying the image of the green component. Is a green organic EL element 20 G that emits light in the green region wavelength, and a blue organic EL element 20 B that emits light in the blue region wavelength is on the back of the liquid crystal display element 21 B that displays an image of the blue component. Each is located. The image displayed on each liquid crystal display element is illuminated by the corresponding organic EL element, synthesized as a color image by the dichroic prism 22, enlarged by the projection lens 23, and projected on the screen 24. The light emitting region formed by each organic EL element in the present embodiment is uniform over the entire surface of each element, and the light emitting layer structure preferably has an optical microresonator structure. The micro-resonator structure allows emission of light with a narrow-band spectrum with peaks at specific wavelengths (for example, 620 nm for red, 535 nm for green, and 47 Onm for blue), and The directivity of the emitted light can be sharpened in the front direction of the element. The narrow-band light-emitting spectrum enables a color image with high purity to be displayed, and the strong directivity increases the amount of light that can pass through the projection lens, thereby enabling a bright image to be displayed.

In particular, in the present embodiment, a pulse current supply source 25R, 25G, 25B is connected to each organic EL element 20R, 20G, 2OB, and each organic EL element emits light in a pulsed manner.

The size of the display area in each of the liquid crystal display elements 21R, 21G, and 2IB is, for example, 0.9 inches diagonally, and the light emitting area in each of the organic EL elements 20R, 20G, and 20B is used to illuminate this area. Is 1 inch diagonally, for example. When driving an organic EL element that emits light in such a large light-emitting area with a direct current, heat is accumulated in the element when a large amount of current is passed in order to emit light with high luminance. Is changed, which causes the life of the element to be shortened. Therefore, preventing the accumulation of heat by driving the element in a noise-less manner is effective for extending the life.

The temporally averaged luminance of the pulsed and driven organic EL element is the product of the luminance determined by the peak current of one pulse and the duty of the pulse (the ratio of the current application time to one cycle of the pulse).

The frequency of the pulse current needs to be high enough to avoid flickering, for example, about 100 Hz. Figure 5A shows an example of the pulse current waveform.The peak current I0 is 0.5 A, the frequency is 100 Hz (period 10 ms ec), and the pulse duty is 50% (pulse width 5 msec). Can be.

Since the display device has red, green, and blue organic EL elements, it is necessary to adjust the light emission luminance of the organic EL elements of each color in order to balance each color. Also, display device The luminance of the organic EL element decreases during use.t Although the degree of this luminance decrease is different for each color organic EL element, it is not shown, but the luminance of each color organic EL element is independent. Means that can be adjusted.

Since each organic EL element is driven by a pulse, the luminance can be adjusted by adjusting the peak current of the pulse current or the duty of the pulse. Figure 5 shows this example. Assume that the pulse current shown in Fig. 5A is the reference. Figure 5B shows an example in which the pulse period and duty are the same as the reference, and the brightness is increased by increasing the peak current to I! = 0.6A. Figure 5C shows an example in which the pulse period and the peak current are the same as the reference, and the brightness is increased by increasing the pulse duty from 50% to 70%. Figure 5D shows an example in which the peak current is the same as the reference, the pulse frequency is reduced from 100 Hz to 70 Hz, and the brightness is increased with a duty of 80%.

Further, it is preferable that the frequency supplied to the pulses supplied to the organic EL elements 20R, 20G, and 20B be the same, and the supplied timing (phase) be the same. FIG. 6 shows an example of the timing of such pulse application. In this case, for the brightness of red EL element (2 OR), green EL elements (20G), and blue EL elements wave height of pulses applied to each of the (20B) s (peak current _{_{_{I R, I G, I B}}} ) It is controlled by adjustment. In a display device adopting such a pulse application method, the degree of color separation is suppressed as compared with the case where there is a deviation in the pulse, and the display color balance is improved. Also, the pulse frequency itself may be the same, and the pulse width may be changed for each color of R, G, B to the extent that it can be visually observed.

A display device according to a third embodiment of the present invention will be described with reference to FIG. FIG. 7 is a sectional view of a main optical system constituting the projection type liquid crystal display device. The difference from the configuration of the second embodiment is that only one liquid crystal display element 30 is provided.

Opposite to the corresponding surface of the dichroic prism 22, a red organic EL element 2OR emitting at a wavelength in the red region, a green organic EL element 20G emitting at a wavelength in the green region, and blue emitting at a wavelength in the blue region. An organic EL element 20B is provided.

Light emitted from each organic EL element is synthesized by the dichroic prism 22,

Corrected form (Rule 91) It becomes white light. The white light illuminates the liquid crystal display element 30 arranged opposite to the light exit surface of the dichroic prism 22 from behind. The liquid crystal display element 30 has a color filter in its pixel, and can display a color image by illumination with white light. The image displayed on the liquid crystal display element 30 is enlarged by a projection lens 23 and projected on a screen 24.

A pulse current supply source 25 R, 25 G, 25 B is connected to each organic EL element 20 R, 20 G, 20 B, and each organic EL element is pulse-driven, and is driven in accordance with the pulse application. It emits light.

Since the display device is equipped with red, green, and blue organic EL elements, it is necessary to adjust the emission luminance of the organic EL elements of each color in order to balance each color. Although the luminance of the organic EL element decreases during use of the display device, the degree of the luminance decrease is different for each color of the organic EL element. There is a need for a means that can independently adjust the brightness of the image.

Since each organic EL element is driven by a pulse, the luminance can be adjusted by adjusting the peak current of the pulse current or the duty of the pulse as described in the second embodiment. In addition, the timing (phase) of applying a pulse to each of the organic EL elements 20R, 20G, and 20B elements can be made the same to improve the display color balance.

A display device according to a fourth embodiment of the present invention will be described with reference to FIG. The display device according to the present embodiment is a head-up display in which an image of a liquid crystal display element is superimposed and displayed on a front view by a complier arranged on a windshield of an automobile, and FIG. It is. The display device of this embodiment displays only a green image.

The liquid crystal display element 21 G is illuminated by the organic EL element 20 G that emits green light and is pulsed by the pulse current supply source 25 G. The image displayed on the liquid crystal display element 21G is viewed from the front by the optical system composed of the relay lens 40, the mirror 41, and the concave holographic combiner 42 in front of the holographic computer combiner. 4 Overlaid on 5 PT

14

The organic EL device 20G has a microcavity in its light emitting layer structure, and can emit light having a narrow band spectrum having a peak at a specific wavelength (for example, 5355 nm). Since the holographic complier 42 is a holographic element, its optical characteristics are sensitive to wavelength changes, and the narrower the light emission spectrum of the light source, the more the occurrence of aberration can be suppressed. From this point, a combination of a holographic combiner and an organic EL element having a micro-resonator structure in a head-up display is preferable.

A display device according to a fifth embodiment of the present invention will be described with reference to FIG. The display device according to the present embodiment is a head-up display in which an image of a liquid crystal display element is superimposed and displayed on a front view by a combiner as in the fifth embodiment, and FIG. 9 shows the main optical system. It is sectional drawing. The head-up display of the present embodiment can display a single color image.

The portion for generating the display image is the same as the structure described in the second embodiment, except that three liquid crystal display elements 2 1 R and 2 corresponding to the three primary colors are arranged around the dichroic prism 22. It consists of 1 G and 2 IB, and red organic EL element 20 R, green organic EL element 20 G and blue organic EL element 20 B arranged on the back of each, and each organic EL element is Pulsed by pulse current sources 25R, 25G, 25B.

The color image synthesized by the dichroic prism 22 is distant in front of the holographic compiler by an optical system composed of a relay lens 50, a mirror 51, and a concave holographic compiler 52. Displayed in front view 4 5.

Each of the three organic EL elements, 20 R, 20 G and 20 B, has a microcavity in its light emitting layer structure and has a specific wavelength (for example, 62 nm, 5355 nm, 470 nm). ) Can emit light having a narrow-band spectrum having a peak at the peak. By constructing the holographic compiner 52 by superimposing holographic elements whose reflection characteristics are optimized for each wavelength, three wavelengths from each organic EL element are reflected, and other areas are reflected. Wavelength of light can be transmitted JP

Fifteen

Compiler can be configured. The complier designed in this way has a high reflectance to the display image light 53 and can also increase the transmittance of light in the front view 45, so that a bright display image is superimposed on a bright front view. It can be displayed. In the fourth and fifth embodiments, a combination of a holographic complier and a relay lens is shown as an optical system for displaying an image of a liquid crystal display element in a distant front. It is also possible to apply an optical system that combines a compensator composed of a body multilayer film and an appropriate lens system.

Next, a display device according to a sixth embodiment of the present invention will be described. The basic structure of the display device of this embodiment is the same as the structure shown in FIG. 4 according to the second embodiment, but is composed of organic EL elements (20R, 20G, 20B). The structure inside the light source differs. That is, in the present embodiment, the organic EL element constituting the light source forms a planar structure composed of one-dimensional stripe-shaped light emitting region patterns as shown in FIG. 3, which can be employed in the first embodiment. Pulse driving is performed by a pulse current supply source (25R, 25G, 25B) connected to each EL element shown in FIG.

In the light source according to the present embodiment, the light emitting regions of the organic EL element are arranged discretely, a path for releasing heat generated at the time of light emission of the EL element is formed, and heat generation of the element for pulse driving the organic EL element is performed. The time can be intermittent, and the accumulation of heat in the entire light source including the array of EL elements can be significantly prevented. As a result, in the display device, the life of the light source can be prolonged, and a display having stable luminance can be realized.

In the present embodiment, a one-dimensional striped pattern is shown as a light emitting region composed of an organic EL element in the light source. However, for example, a two-dimensional light emitting portion shown in FIG. 2 that can be adopted in the first embodiment is arranged. A light source can be used. Furthermore, in the pulse driving, the frequency of the pulse applied to the light source composed of each organic EL element (20R, 20G, 20B) is made the same, and the timing of supplying these for each color It is preferable that (phase) be the same (in-phase) as shown in FIG. In this case, it can be controlled by adjusting the pulse peak value of the luminance (peak current _{_{_{I R, Ι π, Ι Β}}} ). Such pulse application method In a display device adopting, the degree of color separation is suppressed as compared with the case where there is a pulse shift, and the balance of display colors is further improved. Also, the pulse frequency itself may be the same, and the pulse width may be changed by each color of R, G, B to the extent that it can be visually observed.

Further, the combination of the arrangement of the organic EL elements and the pulse driving in the light source according to the present embodiment is applied to a structure in which a liquid crystal display element is provided for each light source of each color in the structure shown in FIG. As shown in FIG. 7, it is also possible to combine the light from the light sources of the respective colors and apply the light to one liquid crystal display element.

As described above, in the second to sixth embodiments, it has been described that three sets of liquid crystal display elements and organic EL elements for displaying respective components of red, green, and blue are used to display a color image. Depending on the application, it is also possible to configure a display device using a combination of only two colors such as red and green.

The present invention is not limited to the second to sixth embodiments, and can be applied to a display device using an organic EL element as a light source, and a video camera for viewing an enlarged virtual image of a liquid crystal display element through a lens. The present invention can also be applied to a display device such as a viewfinder. As a display element, a spatial light modulator capable of modulating transmitted light can be used in addition to a liquid crystal display element.

According to the display devices according to the second to sixth embodiments of the present invention, in a display device that illuminates a display device using an organic EL device that emits red, green, and blue light with high brightness, the display device uses heat accumulation. The deterioration of the organic EL element can be suppressed, and the color balance of each organic EL element can be adjusted by controlling both the peak current and the duty of the noise current.

Claims

The scope of the claims

(1) A light source, wherein a plurality of organic electroluminescent elements arranged one-dimensionally or two-dimensionally are formed on the same substrate, and the plurality of organic electroluminescent elements are simultaneously turned on.

(2) The light source according to claim 1, wherein the plurality of organic electroluminescent elements emit light in one of three primary colors.

(3) The light source according to claim 1 or 2, wherein the organic electroluminescent element includes an optical microresonator.

(4) The organic electric field is formed at an intersection of an anode formed in a striped shape in a first direction on the substrate and a striped cathode formed in a second direction orthogonal to the first direction. The light source according to any one of claims 1 to 3, wherein a light emitting element is formed.

(5) The light source according to any one of claims 1 to 3, wherein a light emitting unit is arranged one-dimensionally on the substrate.

(6) A display device, wherein a display element is illuminated by the light source according to any one of claims 1 to 5.

(7) When the distance between the adjacent organic electroluminescent elements in the light source is P and the distance from the organic electroluminescent element to the display surface of the display element is D, D is at least 10 times P. 7. The display device according to claim 6, wherein:

(8) The display device according to claim 6 or 7, wherein the display element is a liquid crystal display element.

(10) First organic electroluminescent element that emits light in the red region, emits light in the green region A first, a second, and a third display element illuminated by the second organic electroluminescent element and the third organic electroluminescent element that emits light in the blue region, and A display device comprising: a combining optical system for combining images displayed on the first, second, and third display elements; and an optical system for enlarging and displaying an image combined by the combining optical system. The first, second and third organic electroluminescent elements each have a light-emitting area having a size similar to the display area of the first, second and third display elements, and the first, second and A display device, wherein a pulse current is supplied to each of the organic electroluminescent elements to cause the third organic electroluminescent element to emit light.

(11) The first organic electroluminescent device emitting light in the red region, the second organic electroluminescent device emitting light in the green region, and the third organic electroluminescent device emitting light in the blue region A synthetic optical system for synthesizing emitted light from the respective organic electroluminescent elements, a display element illuminated by the light synthesized by the synthetic optical system, and an image displayed on the display element. An optical system, wherein the first, second, and third organic electroluminescent elements include a light-emitting area having a size substantially equal to a display area of the display element, and the first, second, and A display device, wherein a pulse current is supplied to each of the organic electroluminescent elements in order to cause the third organic electroluminescent element to emit light.

(12) The display device according to any one of claims 9 to 11, wherein the display device is a liquid crystal display device.

(13) The method according to any one of claims 9 to 9, wherein at least one of a peak current, a frequency, and a pulse width of the pulse current is controlled to adjust the luminance of the organic electroluminescent element. A display device according to any one of paragraphs 11 to 11.

(14) In order to adjust the color of a displayed image, at least one of the peak current, frequency, and pulse width of the pulse current supplied to the first, second, and third organic electroluminescent elements is adjusted. 12. The display device according to claim 10, wherein each of the organic electroluminescent elements is independently controlled.

(15) The display device according to any one of claims 9 to 14, wherein the organic electroluminescent element has an optical microresonator structure. (16) The display according to the item (10) or (11), wherein the timing at which a pulse is supplied to each of the first, second, and third organic electroluminescent elements is the same.

(18) A plurality of first organic electroluminescent elements which emit light in a plurality of red regions arranged one-dimensionally or two-dimensionally on the same substrate are formed, and the plurality of organic electroluminescent elements are simultaneously turned on. A first light source and a second organic electroluminescent element that emits light in a plurality of green regions arranged one-dimensionally or two-dimensionally on the same substrate are formed, and the plurality of organic electroluminescent elements are formed. A second light source that is turned on at the same time and a third organic electroluminescent element that emits light of a plurality of blue regions arranged one-dimensionally or two-dimensionally on the same substrate are formed. A third light source that simultaneously turns on the electroluminescent elements, at least one display element that is illuminated by the light source composed of the organic electroluminescent elements, and an optical system that enlarges and displays an image formed by the display elements. A display device comprising: the first light A pulse current is supplied to each of the organic electroluminescent elements in the source, the organic electroluminescent element in the second light source, and the third organic electroluminescent element in the third light source. A display device characterized by being performed.

(19) The display device according to claim 18, wherein the timing at which a pulse is supplied to each of the first, second, and third organic electroluminescent elements is the same. Claims of amendment

[February 7, 2000 (07.0 2.00) Accepted by the International Bureau: New Claim 20 added; other claims unchanged. (1 page)]

(16) The display according to the item (10) or (11), wherein the timing at which a pulse is supplied to each of the first, second, and third organic electroluminescent elements is the same.

(17) A plurality of one-dimensionally or two-dimensionally arranged organic electroluminescent elements are formed on the same substrate, and a light source in which the plurality of organic electroluminescent elements are simultaneously turned on, and illumination by the light source. A display device comprising: a display element to be displayed; and an optical system for displaying an image displayed on the display element in an enlarged manner. In order to cause the organic electroluminescent element in the light source to emit light, a pulse current is applied to the organic electroluminescent element. A display device characterized by being supplied.

(18) A plurality of first organic electroluminescent elements which emit light in a plurality of red regions arranged one-dimensionally or two-dimensionally on the same substrate are formed, and the plurality of organic electroluminescent elements are simultaneously turned on. A first light source and a second organic electroluminescent element that emits light in a plurality of green regions arranged one-dimensionally or two-dimensionally on the same substrate. A second light source in which the elements are turned on at the same time and a third organic electroluminescent element which emits light in a plurality of blue regions arranged one-dimensionally or two-dimensionally on the same at are formed. A third light source in which a plurality of organic electroluminescent elements are turned on at the same time, at least one display element illuminated by the light source including the organic electroluminescent elements, and an image formed by the display element is enlarged and displayed. A display device comprising: an optical system; A pulse current is supplied to each of the organic electroluminescent elements in the source, the organic electroluminescent element in the second light source, and the third organic electroluminescent element in the third light source. A display device characterized by being performed.

(19) The display device according to claim 18, wherein the timing at which a pulse is supplied to each of the first, second, and third organic electroluminescent elements is the same.

(ii) (20) The light source according to claim 1, wherein all the organic electroluminescent elements on the substrate are simultaneously turned on.

Paper captured (Article 19 of the Convention)